A low-cost, low-carbon-emission silicon carbide ceramic matrix composite material and its preparation method

Abstract

This invention discloses a silicon carbide ceramic matrix composite material and its preparation method. The composite material has a fiber content of 50-90% and a silicon carbide matrix content of 7-45%, with a tensile strength of 300-400 MPa and a fracture strain of 0.5-1.5%. The preparation method includes the following steps: (1) impregnating a precursor polycarbosilane into a preform; (2) curing and crosslinking at 200-400℃ for 1-5 hours; (3) pyrolyzing at 600-1000℃ for 1-5 hours; (4) repeating steps (1)(2)(3) for 1-5 short cycles; (5) sintering at 1000-1250℃ for 1-3 hours; and (6) repeating steps (1)(2)(3)(4)(5) for 1-6 long cycles to obtain a low-cost, low-carbon-emission silicon carbide ceramic matrix composite material. Compared with traditional methods, silicon carbide ceramic matrix composites have 150-200% higher strength, 200-300% higher fracture strain, 30-50% lower cost, 30-60% shorter cycle time, and more than 25% lower carbon emissions.

Description

Technical Field

[0001] This invention relates to a ceramic matrix composite material and its preparation method, and more particularly to a low-cost, low-carbon-emission silicon carbide ceramic matrix composite material and its preparation method. Background Technology

[0002] Silicon carbide ceramic matrix composites are renowned for their high hardness, low density, excellent oxidation resistance, and high-temperature resistance, showing broad application prospects in aerospace, automotive, defense, energy, and electronic devices. Traditional preparation methods are typically costly and complex, which limits their large-scale commercial application. Therefore, exploring a low-cost, efficient method for preparing silicon carbide ceramic matrix composites has significant theoretical and practical value.

[0003] Existing technologies and their limitations: Currently, the main technologies used to prepare silicon carbide ceramic matrix composites include precursor organic polymer impregnation and pyrolysis (PIP), chemical vapor infiltration (CVI), and reactive melt infiltration (RMI). These technologies each have their own characteristics, but also certain limitations.

[0004] PIP (Pollution-Injection-Cure-Pyrolysis) is an impregnation-curing-pyrolysis process based on organic precursors that can effectively prepare composite materials with complex shapes and structures. This method is simple to operate and suitable for large-scale production, but the entire preparation process is lengthy due to the need for multiple cycles, and the material cost is relatively high.

[0005] CVI (Chemical Vapor Interaction) deposits silicon carbide ceramic materials in porous preforms via chemical vapor deposition, allowing for precise control over the material's microstructure. However, the CVI process typically takes a long time to complete and requires sophisticated equipment, leading to increased costs.

[0006] RMI uses liquid silicon metal as an intermediate medium to react the metal with the ceramic fiber preform at high temperatures to generate the desired composite material. This method can complete the preparation in a relatively short time, but because the silicon infiltration temperature is as high as 1400-1600℃, it causes significant damage to the silicon carbide fibers, and the overall cost remains high.

[0007] Despite the progress made by the above technologies in the preparation of silicon carbide ceramic matrix composites, some key challenges remain:

[0008] Cost issues: Existing preparation methods usually require expensive raw materials and complex equipment, resulting in high finished product costs.

[0009] Process complexity: Some technologies, such as CVI, require a long deposition process, which increases manufacturing cycle time and energy consumption.

[0010] Performance consistency: How to maintain the consistency and reliability of material properties while reducing costs is also an important issue. Summary of the Invention

[0011] In light of the above background, this invention aims to propose a PIP (Polyin-In-Place) technology using polycarbosilane as a precursor to prepare high-performance, low-cost silicon carbide ceramic matrix composites through a cyclic process of impregnation-curing-pyrolysis-sintering. This method not only reduces material costs but also improves the mechanical properties and thermal stability of the materials, providing a new approach for the industrial production of high-performance composite materials.

[0012] The present invention is characterized in that the total component of the composite material is 50-90%, the total component of the silicon carbide matrix is ​​7-45%, the tensile strength is 300-400 MPa, and the fracture strain is 0.5-1.5%.

[0013] The present invention is characterized by the preparation method of the composite material, which uses polycarbosilane as a precursor and prepares a high-performance silicon carbide ceramic matrix composite material through a cyclic process of impregnation-curing-pyrolysis-sintering. The preparation method includes the following sequential steps: (1) impregnating the precursor polycarbosilane into a preform; (2) curing and crosslinking at 200-400℃ for 1-5 hours; (3) pyrolyzing at 600-1000℃ for 1-5 hours; (4) repeating steps (1)(2)(3) for 1-5 short cycles; (5) sintering at 1000-1250℃ for 1-3 hours; (6) repeating steps (1)(2)(3)(4)(5) for 1-6 long cycles to obtain a low-cost, low-carbon emission silicon carbide ceramic matrix composite material.

[0014] Compared with existing materials and technologies, the present invention has the following beneficial effects: (1) The fiber volume fraction is high, the strength of the composite material is increased by 150-200%, and the fracture strain is increased by 200-300%; (2) The fiber volume fraction is high, the amount of polycarbosilane used is reduced, and the cost of the composite material is reduced by 30-50%; (3) The fiber volume fraction is high, and the performance consistency of the composite material is improved; (4) The number of cycles of impregnation-curing-pyrolysis-sintering is small, the high temperature damage to the fiber is small, and the fiber performance is maintained; (5) The total number of cycles and total time of high temperature sintering of the composite material are shortened by more than 75%, the manufacturing cycle is shortened by 30-60%, the energy consumption cost is reduced by more than 50%, and the carbon emission is reduced by more than 25%, which is a low-carbon emission preparation method. Detailed Implementation

[0015] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0016] Example 1: Bearing Pipe Material and Preparation

[0017] The silicon carbide fiber tube preform has an inner diameter of 100 mm, an outer diameter of 135 mm, and a length of 100 mm. It is fixed by graphite molds on both the inside and outside. The volume fraction of silicon carbide fiber is 90%, and it is tightly wound with fine fiber cloth. First, the preform is placed in a polycarbosilane solution, (1) impregnated with 3 MPa pressure for 2 hours; (2) then cured at 300℃ under normal pressure for 2 hours; (3) then pyrolyzed at 600℃ for 1 hour; (4) the above impregnation-curing-pyrolysis process is repeated for 1 cycle; then (5) sintering at 1150℃ for 2 hours; (6) the above steps (1)(2)(3)(4)(5) are repeated for 1 cycle to obtain a low-cost composite material. The sintering temperature of the second step (5) is 1200℃ and held for 3 hours. After the first step (5) is completed, the preform is demolded and rough machined to obtain the required surface dimensions; after the step (6) is completed, the surface is finely machined to obtain the required bearing tube. The composite material has a tensile strength of 380 MPa and a fracture strain of 1.5%.

[0018] Example 2: Brake Disc Materials and Preparation

[0019] Carbon fiber nonwoven fabric mesh, with an inner diameter of 200mm, an outer diameter of 300mm, and a thickness of 20mm, is fixed by graphite molds both inside and outside. The volume fraction of carbon fiber is 45±5%, and it is formed by nonwoven bonding and puncture. The preform is first placed in a polycarbosilane solution, (1) vacuum impregnated for 2 hours; (2) then cured at 400℃ under normal pressure for 2 hours; (3) then pyrolyzed at 800℃ for 1 hour; (4) the above impregnation-curing-pyrolysis process is repeated for 5 cycles; (5) sintered at 1250℃ for 2 hours; (6) the above steps (1)(2)(3)(4)(5) are repeated for 5 cycles to obtain a low-cost composite material. After the third step (5), the preform is demolded and processed to obtain the required surface dimensions; after the step (6), the surface is finished to obtain the required brake disc component. The tensile strength of the composite material is 320MPa, and the fracture strain is 0.7%.

[0020] Example 3: Blade Materials and Preparation

[0021] The silicon carbide fiber blade preform is 80 mm long, 50 mm wide, and 10 mm thick. It is fixed internally and externally by graphite molds. The volume fraction of silicon carbide fiber is 60 ± 5%, and it is formed by three-dimensional, four-dimensional weaving of small tows of silicon carbide fiber. The fabrication process includes four long cycles, as follows:

[0022] First long loop:

[0023] (1) Place the preform into a polycarbosilane solution and vacuum impregnate for 1 hour; (2) Then cure at 400°C under normal pressure for 5 hours; (3) Then pyrolyze at 600°C for 1 hour; (4) Repeat the above impregnation-curing-pyrolysis process for 5 short cycles; (5) Sinter at 1000°C for 3 hours; (6) Perform the second long cycle.

[0024] The second long cycle:

[0025] (1) After the first long cycle, the preform is placed in a polycarbosilane solution and impregnated under vacuum at 1 MPa for 2 hours; (2) Then it is cured at 350°C under normal pressure for 3.5 hours; (3) Then it is pyrolyzed at 700°C for 1.5 hours; (4) The above impregnation-curing-pyrolysis process is repeated for 4 short cycles; (5) Sintering is performed at 1100°C for 3 hours; (6) The third long cycle is performed.

[0026] Demolding and rough machining removes the hard shell from the surface, which is beneficial for further impregnation and densification inside the blade.

[0027] The third long cycle:

[0028] (1) After the second long cycle, the preform is placed in a polycarbosilane solution and impregnated under vacuum at 2MPa for 3 hours. (2) Then it is cured at 300℃ under normal pressure for 2 hours. (3) Then it is pyrolyzed at 800℃ for 1 hour. (4) The above impregnation-curing-pyrolysis process is repeated for 2 short cycles. (5) It is sintered at 1150℃ for 2 hours. (6) The fourth long cycle is performed.

[0029] The fourth long cycle:

[0030] (1) After the third long cycle, the preform is placed in a polycarbosilane solution and impregnated under vacuum at 3MPa for 4 hours; (2) Then it is cured at 400℃ under normal pressure for 1 hour; (3) Then it is pyrolyzed at 900℃ for 0.5 hours; (4) The above impregnation-curing-pyrolysis process is repeated for one short cycle; (5) Sintered at 1250℃ for 2 hours to obtain the desired composite material.

[0031] It undergoes fine machining and surface CVD silicon carbide coating treatment.

[0032] The composite material has a tensile strength of 350 MPa and a fracture strain of 1.0%, and its cost is reduced by 30% and carbon emissions are reduced by 25% compared with traditional methods.

Claims

1. A method for producing a low-cost, low-carbon emission silicon carbide ceramic matrix composite material composed of a fiber and silicon carbide, characterized by The composite material comprises 50-90% fiber and 7-45% silicon carbide matrix, with a tensile strength of 300-400 MPa and a fracture strain of 0.5-1.5%. The preparation method uses polycarbosilane as a precursor and employs a cyclic process of impregnation-curing-pyrolysis-sintering to prepare a high-performance silicon carbide ceramic matrix composite material. The method is characterized by the following sequential steps: (1) Impregnate the precursor polycarbosilane into the preform by vacuum impregnation and pressure impregnation; (2) Curing and crosslinking treatment at 200-400℃ for 1-5 hours; (3) Pyrolysis at 600-1000℃ for 1-5 hours; (4) Repeat steps (1)(2)(3) for 1 to 5 short cycles; (5) Sinter at 1000-1250℃ for 1-3 hours; (6) Repeat steps (1)(2)(3)(4)(5) for 1 to 6 long cycles to obtain low-cost, low-carbon-emission silicon carbide ceramic matrix composite materials.